He is over 35, a natural born citizen, and has lived in the US for 14 years. He was impeached, but not convicted. Accused of insurrection, but the wheels of justice turned too slowly.
That’s the extent of the legal requirements to be eligible to be President. The theory was that any other social disqualifications would be handled at the ballot box.
That theory is now proven to be incorrect, but fixing it takes a constitutional amendment.
For federal stuff, yes … probably, it’s never been tested, but the current SCOTUS won’t stop him.
Not for state crimes. Like the 34 felony counts in NY. But enforcement of any sentence (probably financial) is unclear. Also unprecedented.